test.py: Skip pair/vanish in P2P mode for now

It times the socket failures from when the peer drops off the peer list,
which the ad hoc server updates in wall time, so on macOS CI at 600% the
failure lands under a second after it instead of 1-2s. The relay run
still covers it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test.py

@@ -627,7 +627,12 @@ pair_known_failures = {
     # listener, so it times out instead.
     "net/adhoc/pair/basic",
   ],
-  "p2p": [],
+  "p2p": [
+    # Times the send and recv failures from when the peer drops off the peer list. In P2P the socket
+    # error comes from the host's TCP, while the peer list comes from the ad hoc server in wall time,
+    # so at CI's speeds the failure can land within the first second (macOS CI) instead of 1-2s.
+    "net/adhoc/pair/vanish",
+  ],
 }
 if platform.system() == "Windows":
   # Windows retries a refused TCP connect for about a second before reporting it, which at the tests'